Clinical Trials

Fragile X syndrome (FraX) is the most common known heritable cause of human intellectual
disability. Though recent research has revealed much about the genetic and neurobiological
bases of FraX, knowledge about specific and effective treatments for affected individuals is
lacking. Based on information from both human and animal studies, one cause of intellectual
disability in FraX may be related to deficits in a particular brain neurotransmitter system
(the "cholinergic" system). Thus, the investigators propose to use a specific medication,
donepezil, to augment cholinergic system in adolescents affected by FraX. If found to be
effective, the knowledge generated by this research may also be relevant to other
developmental disorders that share common disease pathways with FraX.

Stanford is currently not accepting patients for this trial.For more information, please contact Mai K Manchanda, AB, 650-704-9763.

Abstract

While a relationship between disruption of circadian rhythms and the progression of cancer has been hypothesized in field and epidemiologic studies, it has never been unequivocally demonstrated. We determined the circadian rhythm of cortisol and sleep in women with advanced breast cancer (ABC) under the conditions necessary to allow for the precise measurement of these variables. Women with ABC (n = 97) and age-matched controls (n = 24) took part in a 24-h intensive physiological monitoring study involving polysomnographic sleep measures and high-density plasma sampling. Sleep was scored using both standard clinical metrics and power spectral analysis. Three-harmonic regression analysis and functional data analysis were used to assess the 24-h and sleep-associated patterns of plasma cortisol, respectively. The circadian pattern of plasma cortisol as described by its timing, timing relative to sleep, or amplitude was indistinguishable between women with ABC and age-matched controls (p's > 0.11, t-tests). There was, however, an aberrant spike of cortisol during the sleep of a subset of women, during which there was an eightfold increase in the amount of objectively measured wake time (p

Abstract

Autism spectrum disorder (ASD) is increasingly recognized as a public health issue. Irritability and aggression (IA) often negatively affect the lives of people with ASD and their families. Although many medications have been tested for IA in ASDs in randomized controlled trials (RCTs), critical quantitative analyses of these trials are lacking in the literature.To systematically review and quantitatively analyze the efficacy and safety of pharmacologic treatments for IA in youth with ASD.Studies were identified from Medline, PsycINFO, Embase, and review articles.Original articles on placebo-controlled RCTs of pharmacologic treatments of IA in youth age 2 to 17 years with ASD were included. Data items included study design, study goals, details of study participants, details of intervention, study results, statistical methods, side effects, and risks of bias. The primary study outcome measure was the effect size of reduction in the Aberrant Behavioral Checklist-Irritability (ABC-I) scores in the medication group, as compared with placebo, in RCTs using parallel groups design.Forty-six RCTs were identified. Compared with placebo, 3 compounds resulted in significant improvement in ABC-I at the end of treatment. Risperidone and aripiprazole were found to be the most effective, with the largest effect sizes. Sedation, extrapyramidal sides effects, and weight gain were assessed quantitatively.Although risperidone and aripiprazole have the strongest evidence in reducing ABC-I in youth with ASD, a few other compounds also showed significant efficacy with fewer potential side effects and adverse reactions in single studies.

Abstract

The framework of principal stratification provides a way to think about treatment effects conditional on post-randomization variables, such as level of compliance. In particular, the complier average causal effect (CACE) - the effect of the treatment for those individuals who would comply with their treatment assignment under either treatment condition - is often of substantive interest. However, estimation of the CACE is not always straightforward, with a variety of estimation procedures and underlying assumptions, but little advice to help researchers select between methods. In this article, we discuss and examine two methods that rely on very different assumptions to estimate the CACE: a maximum likelihood ('joint') method that assumes the 'exclusion restriction,' (ER) and a propensity score-based method that relies on 'principal ignorability.' We detail the assumptions underlying each approach, and assess each methods' sensitivity to both its own assumptions and those of the other method using both simulated data and a motivating example. We find that the ER-based joint approach appears somewhat less sensitive to its assumptions, and that the performance of both methods is significantly improved when there are strong predictors of compliance. Interestingly, we also find that each method performs particularly well when the assumptions of the other approach are violated. These results highlight the importance of carefully selecting an estimation procedure whose assumptions are likely to be satisfied in practice and of having strong predictors of principal stratum membership.

Abstract

There is a paucity of randomized clinical trials (RCTs) for adolescents with bulimia nervosa (BN). Prior studies suggest cognitive-behavioral therapy adapted for adolescents (CBT-A) and family-based treatment for adolescent bulimia nervosa (FBT-BN) could be effective for this patient population. The objective of this study was to compare the relative efficacy of these 2 specific therapies, FBT-BN and CBT-A. In addition, a smaller participant group was randomized to a nonspecific treatment (supportive psychotherapy [SPT]), whose data were to be used if there were no differences between FBT-BN and CBT-A at end of treatment.This 2-site (Chicago and Stanford) randomized controlled trial included 130 participants (aged 12-18 years) meeting DSM-IV criteria for BN or partial BN (binge eating and purging once or more per week for 6 months). Outcomes were assessed at baseline, end of treatment, and 6 and 12 months posttreatment. Treatments involved 18 outpatient sessions over 6 months. The primary outcome was defined as abstinence from binge eating and purging for 4 weeks before assessment, using the Eating Disorder Examination.Participants in FBT-BN achieved higher abstinence rates than in CBT-A at end of treatment (39% versus 20%; p = .040, number needed to treat [NNT] = 5) and at 6-month follow-up (44% versus 25%; p = .030, NNT = 5). Abstinence rates between these 2 groups did not differ statistically at 12-month follow-up (49% versus 32%; p = .130, NNT = 6).In this study, FBT-BN was more effective in promoting abstinence from binge eating and purging than CBT-A in adolescent BN at end of treatment and 6-month follow-up. By 12-month follow-up, there were no statistically significant differences between the 2 treatments.Study of Treatment for Adolescents With Bulimia Nervosa; http://clinicaltrials.gov/; NCT00879151.

Abstract

Adolescents with Anorexia Nervosa (AN), treated with family-based treatment (FBT) who fail to gain 2.3 kg by the fourth week of treatment have a 40-50% lower chance of recovery than those who do. Because of the high risk of developing enduring AN, improving outcomes in this group of poor responders is essential. This study examines the feasibility and effects of a novel adaptive treatment (i.e., Intensive Parental Coaching-IPC) aimed at enhancing parental self-efficacy related to re-feeding skills in poor early responders to FBT.45 adolescents (12-18 years of age) meeting DSM TR IV criteria for AN were randomized in an unbalanced design (10 to standard FBT; 35 to the adaptive arm). Attrition, suitability, expectancy rates, weight change, and psychopathology were compared between groups.There were no differences in rates of attrition, suitability, expectancy ratings, or most clinical outcomes between randomized groups. However, the group of poor early responders that received IPC achieved full weight restoration (>95% of expected mean BMI) by EOT at similar rates as those who had responded early.The results of this study suggest that it is feasible to use an adaptive design to study the treatment effect of IPC for those who do not gain adequate weight by session 4 of FBT. The results also suggest that using IPC for poor early responders significantly improves weight recovery rates to levels comparable to those who respond early. A sufficiently powered study is needed to confirm these promising findings.

Abstract

To determine if an intervention to reduce maternal distress and address maternal perceptions of infants' vulnerability also reduces perceptions of vulnerability, 105 mothers of premature infants (25- to 34-weeks' gestational age; >600 g) with depression, anxiety, or trauma were randomized to a six- or nine-session intervention or a comparison condition. The outcome was changes in a measure of perception of infant vulnerability between 4 to 5 weeks' and 6 months' postdelivery, the Vulnerability Baby Scale (VBS; B. Forsyth, S. Horwitz, J. Leventhal, & J. Burger, 1996; N. Kerruish, K. Settle, P. Campbell-Stokes, & B. Taylor, 2005). High scores on the VBS were indicative of high levels of perceived infant vulnerability. The perceptions of infants' vulnerability showed significant declines, with no differences across groups or in rate of change. Mothers reporting prior trauma at entry to the study showed much lower perceptions of infants' vulnerability scores under the intervention, Cohen's d = -0.86, p = .01. Given that women with prior trauma are very likely to view their premature infants as vulnerable, this intervention may have important implications for subsequent parenting behaviors and child development.

Abstract

The Aberrant Behavior Checklist-Community (ABC-C; Aman et al., 1995) has been increasingly adopted as a primary tool for measuring behavioral change in clinical trials for individuals with fragile X syndrome (FXS). To our knowledge, however, no study has documented the longitudinal trajectory of aberrant behaviors in individuals with FXS using the ABC-C. As part of a larger longitudinal study, we examined scores obtained on the ABC-C subscales for 124 children and adolescents (64 males, 60 females) with FXS who had two or more assessments (average interval between assessments was approximately 4 years). Concomitant changes in age-equivalent scores on the Vineland Adaptive Behavior Scales (VABS) were also examined. As expected for an X-linked genetic disorder, males with FXS obtained significantly higher scores on all subscales of the ABC-C and significantly lower age-equivalent scores on the VABS than females with FXS. In both males and females with FXS, scores on the Irritability/Agitation and Hyperactivity/Noncompliance subscales of the ABC-C decreased significantly with age, with little to no change occurring over time on the Lethargy/Social Withdrawal, Stereotypic Behavior, and Inappropriate Speech subscales. The decrease in scores on the Hyperactivity/Noncompliance domain was significantly greater for males than for females. In both males and females, age-equivalent scores on the VABS increased significantly over this developmental period. These results establish a basis upon which to evaluate long-term outcomes from intervention-based research. However, longitudinal direct observational studies are needed to establish whether the severity of problem behavior actually decreases over time in this population.

Abstract

We propose a principal stratification approach to assess causal effects in nonrandomized longitudinal comparative effectiveness studies with a binary endpoint outcome and repeated measures of a continuous intermediate variable. Our method is an extension of the principal stratification approach originally proposed for the longitudinal randomized study "Prevention of Suicide in Primary Care Elderly: Collaborative Trial" to assess the treatment effect on the continuous Hamilton depression score adjusting for the heterogeneity of repeatedly measured binary compliance status. Our motivation for this work comes from a comparison of the effect of two glucose-lowering medications on a clinical cohort of patients with type 2 diabetes. Here, we consider a causal inference problem assessing how well the two medications work relative to one another on two binary endpoint outcomes: cardiovascular disease-related hospitalization and all-cause mortality. Clinically, these glucose-lowering medications can have differential effects on the intermediate outcome, glucose level over time. Ultimately, we want to compare medication effects on the endpoint outcomes among individuals in the same glucose trajectory stratum while accounting for the heterogeneity in baseline covariates (i.e., to obtain 'principal effects' on the endpoint outcomes). The proposed method involves a three-step model estimation procedure. Step 1 identifies principal strata associated with the intermediate variable using hybrid growth mixture modeling analyses. Step 2 obtains the stratum membership using the pseudoclass technique and derives propensity scores for treatment assignment. Step 3 obtains the stratum-specific treatment effect on the endpoint outcome weighted by inverse propensity probabilities derived from Step 2.

Abstract

Symptoms of posttraumatic stress disorder are a well-recognized phenomenon in mothers of preterm infants, with implications for maternal health and infant outcomes. This randomized controlled trial evaluated 6-month outcomes from a skills-based intervention developed to reduce symptoms of posttraumatic stress disorder, anxiety, and depression.One hundred five mothers of preterm infants were randomly assigned to (1) a 6- or 9-session intervention based on principles of trauma-focused cognitive behavior therapy with infant redefinition or (2) a 1-session active comparison intervention based on education about the NICU and parenting of the premature infant. Outcome measures included the Davidson Trauma Scale, the Beck Depression Inventory II, and the Beck Anxiety Inventory. Participants were assessed at baseline, 4 to 5 weeks after birth, and 6 months after the birth of the infant.At the 6-month assessment, the differences between the intervention and comparison condition were all significant and sizable and became more pronounced when compared with the 4- to 5-week outcomes: Davidson Trauma Scale (Cohen's d = -0.74, P < .001), Beck Anxiety Inventory (Cohen's d = -0.627, P = .001), Beck Depression Inventory II (Cohen's d = -0.638, P = .002). However, there were no differences in the effect sizes between the 6- and 9-session interventions.A brief 6-session intervention based on principles of trauma-focused cognitive behavior therapy was effective at reducing symptoms of trauma, anxiety, and depression in mothers of preterm infants. Mothers showed increased benefits at the 6-month follow-up, suggesting that they continue to make use of techniques acquired during the intervention phase.

Abstract

To examine longitudinally the adaptive behavior patterns in fragile X syndrome.Caregivers of 275 children and adolescents with fragile X syndrome and 225 typically developing children and adolescents (2-18 years) were interviewed with the Vineland Adaptive Behavior Scales every 2 to 4 years as part of a prospective longitudinal study.Standard scores of adaptive behavior in people with fragile X syndrome are marked by a significant decline over time in all domains for males and in communication for females. Socialization skills are a relative strength as compared with the other domains for males with fragile X syndrome. Females with fragile X syndrome did not show a discernible pattern of developmental strengths and weaknesses.This is the first large-scale longitudinal study to show that the acquisition of adaptive behavior slows as individuals with fragile X syndrome age. It is imperative to ensure that assessments of adaptive behavior skills are part of intervention programs focusing on childhood and adolescence in this condition.

Abstract

We wished to determine whether decreases in N-acetyl aspartate (NAA) and increases in myoinositol (mI) concentrations as a ratio of creatine (Cr) occurred in the dorsolateral prefrontal cortex (DLPFC) of pediatric offspring of parents with bipolar disorder (BD) and a healthy comparison group (HC) over a 5-year period using proton magnetic resonance spectroscopy ((1)H-MRS). Paticipants comprised 64 offspring (9-18 years old) of parents with BD (36 with established BD, and 28 offspring with symptoms subsyndromal to mania) and 28 HCs, who were examined for group differences in NAA/Cr and mI/Cr in the DLPFC at baseline and follow-up at either 8, 10, 12, 52, 104, 156, 208, or 260 weeks. No significant group differences were found in metabolite concentrations at baseline or over time. At baseline, BD offspring had trends for higher mI/Cr concentrations in the right DLPFC than the HC group. mI/Cr concentrations increased with age, but no statistically significant group differences were found between groups on follow-up. It may be the case that with intervention youth at risk for BD are normalizing otherwise potentially aberrant neurochemical trajectories in the DLPFC. A longer period of follow-up may be required before observing any group differences.

Abstract

We wished to determine whether decreases in N-acetyl aspartate (NAA) and increases in myoinositol (mI) concentrations as a ratio of creatine (Cr) occurred in the dorsolateral prefrontal cortex (DLPFC) of pediatric offspring of parents with bipolar disorder (BD) and a healthy comparison group (HC) over a 5-year period using proton magnetic resonance spectroscopy ((1)H-MRS). Paticipants comprised 64 offspring (9-18 years old) of parents with BD (36 with established BD, and 28 offspring with symptoms subsyndromal to mania) and 28 HCs, who were examined for group differences in NAA/Cr and mI/Cr in the DLPFC at baseline and follow-up at either 8, 10, 12, 52, 104, 156, 208, or 260 weeks. No significant group differences were found in metabolite concentrations at baseline or over time. At baseline, BD offspring had trends for higher mI/Cr concentrations in the right DLPFC than the HC group. mI/Cr concentrations increased with age, but no statistically significant group differences were found between groups on follow-up. It may be the case that with intervention youth at risk for BD are normalizing otherwise potentially aberrant neurochemical trajectories in the DLPFC. A longer period of follow-up may be required before observing any group differences.

Abstract

The current study evaluates a treatment intervention developed with the goal of reducing symptoms of posttraumatic stress, depression, and anxiety in parents of premature infants.A total of 105 mothers of preterm infants (25-34 weeks' gestational age; >600 g) were randomized to receive a 6-session intervention developed to target parental trauma as well as facilitate infant redefinition (n = 62) or to an active comparison group (n = 43). Mothers in the intervention group received a combination of trauma-focused treatments, including psychoeducation, cognitive restructuring, progressive muscle relaxation, and development of their trauma narrative. The intervention also incorporated material targeting infant redefinition, defined as the process of changing the mother's negative perceptions of her infant and the parenting experience.Mothers in the intervention group reported a greater reduction in both trauma symptoms (Cohen's d = 0.41, P = .023) and depression (Cohen's d = 0.59, P < .001) compared with the comparison group. Patients under both conditions improved significantly in terms of anxiety, with no differences between groups. Results of the moderator analysis showed that mothers with higher ratings of baseline NICU stress benefited more from the intervention compared with mothers who had lower ratings (P = .036).This short, highly manualized intervention for mothers of preterm infants statistically significantly reduced symptoms of trauma and depression. The intervention is feasible, can be delivered with fidelity, and has high ratings of maternal satisfaction. Given that improvements in mothers' distress may lead to improved infant outcomes, this intervention has the potential for a high public health impact.

Abstract

The current study evaluates a treatment intervention developed with the goal of reducing symptoms of posttraumatic stress, depression, and anxiety in parents of premature infants.A total of 105 mothers of preterm infants (25-34 weeks' gestational age; >600 g) were randomized to receive a 6-session intervention developed to target parental trauma as well as facilitate infant redefinition (n = 62) or to an active comparison group (n = 43). Mothers in the intervention group received a combination of trauma-focused treatments, including psychoeducation, cognitive restructuring, progressive muscle relaxation, and development of their trauma narrative. The intervention also incorporated material targeting infant redefinition, defined as the process of changing the mother's negative perceptions of her infant and the parenting experience.Mothers in the intervention group reported a greater reduction in both trauma symptoms (Cohen's d = 0.41, P = .023) and depression (Cohen's d = 0.59, P < .001) compared with the comparison group. Patients under both conditions improved significantly in terms of anxiety, with no differences between groups. Results of the moderator analysis showed that mothers with higher ratings of baseline NICU stress benefited more from the intervention compared with mothers who had lower ratings (P = .036).This short, highly manualized intervention for mothers of preterm infants statistically significantly reduced symptoms of trauma and depression. The intervention is feasible, can be delivered with fidelity, and has high ratings of maternal satisfaction. Given that improvements in mothers' distress may lead to improved infant outcomes, this intervention has the potential for a high public health impact.

Abstract

OBJECTIVE: There are limited data supporting specific treatments for adults with anorexia nervosa (AN). Randomized clinical trials (RCTs) for adults with AN are characterized by high attrition limiting the feasibility of conducting and interpreting existing studies. High dropout rates may be related to the inflexible and obsessional cognitive style of patients with AN. This study evaluated the feasibility of using cognitive remediation therapy (CRT) to reduce attrition in RCTs for AN. METHOD: Forty-six participants (mean age of 22.7 years and mean duration of AN of 6.4 years) were randomized to receive eight sessions of either CRT or cognitive behavioral therapy (CBT) over 2 months followed by 16 sessions of CBT for 4 months. RESULTS: During the 2-month CRT vs. CBT treatment, rates of attrition were lower in CRT (13%) compared with that of CBT (33%). There were greater improvements in cognitive inefficiencies in the CRT compared with that of the CBT group at the end of 2 months. There were no differences in other outcomes. DISCUSSION: These results suggest that CRT is acceptable and feasible for use in RCTs for outpatient treatment of AN. CRT may reduce attrition in the short term. Adequately powered future studies are needed to examine CRT as an outpatient treatment for AN.

Abstract

The Longitudinal Assessment of Manic Symptoms (LAMS) study was designed to investigate phenomenology and establish predictors of functional outcomes in children with elevated manic symptoms. The purpose of this series of analyses was to determine whether the participants demonstrated different trajectories of parent-reported manic and biphasic symptoms over the first 24 months of follow-up and to describe the clinical characteristics of the trajectories.The 707 participants were initially aged 6-12 years and ascertained from outpatient clinics associated with the four university-affiliated LAMS sites. There were 621 children whose parents/guardians' ratings scored ≥ 12 on the Parent General Behavior Inventory-10-item Mania Form (PGBI-10M) and a matched random sample of 86 children whose parents/guardians' ratings scored ≤ 11 on the PGBI-10M. Participants were seen every six months after the baseline and their parents completed the PGBI-10M at each visit.For the whole sample, manic symptoms decreased over 24 months (linear effect B = -1.15, standard error = 0.32, t = -3.66, p

Abstract

The Longitudinal Assessment of Manic Symptoms (LAMS) study was designed to investigate phenomenology and establish predictors of functional outcomes in children with elevated manic symptoms. The purpose of this series of analyses was to determine whether the participants demonstrated different trajectories of parent-reported manic and biphasic symptoms over the first 24 months of follow-up and to describe the clinical characteristics of the trajectories.The 707 participants were initially aged 6-12 years and ascertained from outpatient clinics associated with the four university-affiliated LAMS sites. There were 621 children whose parents/guardians' ratings scored ≥ 12 on the Parent General Behavior Inventory-10-item Mania Form (PGBI-10M) and a matched random sample of 86 children whose parents/guardians' ratings scored ≤ 11 on the PGBI-10M. Participants were seen every six months after the baseline and their parents completed the PGBI-10M at each visit.For the whole sample, manic symptoms decreased over 24 months (linear effect B = -1.15, standard error = 0.32, t = -3.66, p

Abstract

Premature birth has been associated with multiple adverse maternal psychological outcomes that include depression, anxiety, and trauma as well as adverse effects on maternal coping ability and parenting style. Infants who are premature are more likely to have poorer cognitive and developmental functioning and, thus, may be harder to parent, both as infants and as they get older. In response to these findings, a number of educational and behavioral interventions have been developed that target maternal psychological functioning, parenting, and aspects of the parent-infant relationship. The current study aimed to both develop and evaluate a treatment that integrates, for the first time, effective interventions for reducing symptoms of posttraumatic stress disorder (PTSD) and enhancing maternal-infant interactions. Conclusions from the study indicate that the intervention is feasible, able to be implemented with a high level of fidelity, and is rated as highly satisfactory by participants. Though encouraging, these findings are preliminary, and future studies should strive to reproduce these findings with a larger sample size and a comparison group.

Abstract

Few of the limited randomized controlled trails (RCTs) for adolescent anorexia nervosa (AN) have explored the effects of moderators and mediators on outcome. This study aimed to identify treatment moderators and mediators of remission at end of treatment (EOT) and 6- and 12-month follow-up (FU) for adolescents with AN (N = 121) who participated in a multi-center RCT of family-based treatment (FBT) and individual adolescent focused therapy (AFT). Mixed effects modeling were utilized and included all available outcome data at all time points. Remission was defined as ? 95% IBW plus within 1 SD of the Eating Disorder Examination (EDE) norms. Eating related obsessionality (Yale-Brown-Cornell Eating Disorder Total Scale) and eating disorder specific psychopathology (EDE-Global) emerged as moderators at EOT. Subjects with higher baseline scores on these measures benefited more from FBT than AFT. AN type emerged as a moderator at FU with binge-eating/purging type responding less well than restricting type. No mediators of treatment outcome were identified. Prior hospitalization, older age and duration of illness were identified as non-specific predictors of outcome. Taken together, these results indicate that patients with more severe eating related psychopathology have better outcomes in a behaviorally targeted family treatment (FBT) than an individually focused approach (AFT).

Abstract

Fragile X syndrome (FXS) is the most common known heritable cause of intellectual disability. Prior studies in FXS have observed a plateau in cognitive and adaptive behavioral development in early adolescence, suggesting that brain development in FXS may diverge from typical development during this period.In this study, we examined adolescent brain development using structural magnetic resonance imaging data acquired from 59 individuals with FXS and 83 typically developing control subjects aged 9 to 22, a subset of whom were followed up longitudinally (1-5 years; typically developing: 17, FXS: 19). Regional volumes were modeled to obtain estimates of age-related change.We found that while structures such as the caudate showed consistent volume differences from control subjects across adolescence, prefrontal cortex (PFC) gyri showed significantly aberrant maturation. Furthermore, we found that PFC-related measures of cognitive functioning followed a similarly aberrant developmental trajectory in FXS.Our findings suggest that aberrant maturation of the PFC during adolescence may contribute to persistent or increasing intellectual deficits in FXS.

Abstract

When identification of causal effects relies on untestable assumptions regarding nonidentified parameters, sensitivity of causal effect estimates is often questioned. For proper interpretation of causal effect estimates in this situation, deriving bounds on causal parameters or exploring the sensitivity of estimates to scientifically plausible alternative assumptions can be critical. In this paper, we propose a practical way of bounding and sensitivity analysis, where multiple identifying assumptions are combined to construct tighter common bounds. In particular, we focus on the use of competing identifying assumptions that impose different restrictions on the same non-identified parameter. Since these assumptions are connected through the same parameter, direct translation across them is possible. Based on this cross-translatability, various information in the data, carried by alternative assumptions, can be effectively combined to construct tighter bounds on causal effects. Flexibility of the suggested approach is demonstrated focusing on the estimation of the complier average causal effect (CACE) in a randomized job search intervention trial that suffers from noncompliance and subsequent missing outcomes.

Abstract

The goal of the study was to improve prediction of longitudinal flight simulator performance by studying cognitive factors that may moderate the influence of chronological age.We examined age-related change in aviation performance in aircraft pilots in relation to baseline cognitive ability measures and aviation expertise. Participants were aircraft pilots (N = 276) aged 40-77.9. Flight simulator performance and cognition were tested yearly; there were an average of 4.3 (± 2.7; range 1-13) data points per participant. Each participant was classified into one of the three levels of aviation expertise based on Federal Aviation Administration pilot proficiency ratings: least, moderate, or high expertise.Addition of measures of cognitive processing speed and executive function to a model of age-related change in aviation performance significantly improved the model. Processing speed and executive function performance interacted such that the slowest rate of decline in flight simulator performance was found in aviators with the highest scores on tests of these abilities. Expertise was beneficial to pilots across the age range studied; however, expertise did not show evidence of reducing the effect of age.These data suggest that longitudinal performance on an important real-world activity can be predicted by initial assessment of relevant cognitive abilities.

Abstract

Children with a history of cancer are at increased risk for cognitive impairments, particularly in executive and memory domains. Traditional, in-person cognitive rehabilitation strategies may be unavailable and/or impractical for many of these children given difficulties related to resources and health status. The feasibility and efficacy of implementing a computerized, home-based cognitive rehabilitation curriculum designed to improve executive function skills was examined in these children.A one-arm open trial pilot study of an original executive function cognitive rehabilitation curriculum was conducted with 23 paediatric cancer survivors aged 7-19.Compliance with the cognitive rehabilitation program was 83%, similar to that of many traditional programs. Following the cognitive intervention, participants showed significantly increased processing speed, cognitive flexibility, verbal and visual declarative memory scores as well as significantly increased pre-frontal cortex activation compared to baseline.These results suggest that a program of computerized cognitive exercises can be successfully implemented at home in young children with cancer. These exercises may be effective for improving executive and memory skills in this group, with concurrent changes in neurobiologic status.

Abstract

Mediation analysis uses measures of hypothesized mediating variables to test theory for how a treatment achieves effects on outcomes and to improve subsequent treatments by identifying the most efficient treatment components. Most current mediation analysis methods rely on untested distributional and functional form assumptions for valid conclusions, especially regarding the relation between the mediator and outcome variables. Propensity score methods offer an alternative whereby the propensity score is used to compare individuals in the treatment and control groups who would have had the same value of the mediator had they been assigned to the same treatment condition. This article describes the use of propensity score weighting for mediation with a focus on explicating the underlying assumptions. Propensity scores have the potential to offer an alternative estimation procedure for mediation analysis with alternative assumptions from those of standard mediation analysis. The methods are illustrated investigating the mediational effects of an intervention to improve sense of mastery to reduce depression using data from the Job Search Intervention Study (JOBS II). We find significant treatment effects for those individuals who would have improved sense of mastery when in the treatment condition but no effects for those who would not have improved sense of mastery under treatment.

Abstract

Treatment noncompliance and missing outcomes at posttreatment assessments are common problems in field experiments in naturalistic settings. Although the two complications often occur simultaneously, statistical methods that address both complications have not been routinely considered in data analysis practice in the prevention research field. This paper shows that identification and estimation of causal treatment effects considering both noncompliance and missing outcomes can be relatively easily conducted under various missing data assumptions. We review a few assumptions on missing data in the presence of noncompliance, including the latent ignorability proposed by Frangakis and Rubin (Biometrika 86:365-379, 1999), and show how these assumptions can be used in the parametric complier average causal effect (CACE) estimation framework. As an easy way of sensitivity analysis, we propose the use of alternative missing data assumptions, which will provide a range of causal effect estimates. In this way, we are less likely to settle with a possibly biased causal effect estimate based on a single assumption. We demonstrate how alternative missing data assumptions affect identification of causal effects, focusing on the CACE. The data from the Johns Hopkins School Intervention Study (Ialongo et al., Am J Community Psychol 27:599-642, 1999) will be used as an example.

Abstract

Evidence-based treatment trials for adolescents with anorexia nervosa are few.To evaluate the relative efficacy of family-based treatment (FBT) and adolescent-focused individual therapy (AFT) for adolescents with anorexia nervosa in full remission.Randomized controlled trial.Stanford University and The University of Chicago (April 2005 until March 2009).One hundred twenty-one participants, aged 12 through 18 years, with DSM-IV diagnosis of anorexia nervosa excluding the amenorrhea requirement. Intervention Twenty-four outpatient hours of treatment over 12 months of FBT or AFT. Participants were assessed at baseline, end of treatment (EOT), and 6 months' and 12 months' follow-up posttreatment.Full remission from anorexia nervosa defined as normal weight (?95% of expected for sex, age, and height) and mean global Eating Disorder Examination score within 1 SD of published means. Secondary outcome measures included partial remission rates (>85% of expected weight for height plus those who were in full remission) and changes in body mass index percentile and eating-related psychopathology.There were no differences in full remission between treatments at EOT. However, at both the 6- and 12-month follow-up, FBT was significantly superior to AFT on this measure. Family-based treatment was significantly superior for partial remission at EOT but not at follow-up. In addition, body mass index percentile at EOT was significantly superior for FBT, but this effect was not found at follow-up. Participants in FBT also had greater changes in Eating Disorder Examination score at EOT than those in AFT, but there were no differences at follow-up.Although both treatments led to considerable improvement and were similarly effective in producing full remission at EOT, FBT was more effective in facilitating full remission at both follow-up points.clinicaltrials.gov Identifier: NCT00149786.

Abstract

Dialectical Behavior Therapy for Binge Eating Disorder (DBT-BED) aims to reduce binge eating by improving adaptive emotion-regulation skills. Preliminary findings have been promising but have only compared DBT-BED to a wait-list. To control for the hypothesized specific effects of DBT-BED, the present study compared DBT-BED to an active comparison group therapy (ACGT). Men and women (n=101) meeting DSM-IV BED research criteria were randomly assigned to 20 group sessions of DBT-BED (n=50) or ACGT (n=51). DBT-BED had a significantly lower dropout rate (4%) than ACGT (33.3%). Linear Mixed Models revealed that posttreatment binge abstinence and reductions in binge frequency were achieved more quickly for DBT-BED than for ACGT (posttreatment abstinence rate=64% for DBT-BED vs. 36% for ACGT) though differences did not persist over the 3-, 6-, and 12-month follow-up assessments (e.g., 12-month follow-up abstinence rate=64% for DBT-BED vs. 56% for ACGT). Secondary outcome measures revealed no sustained impact on emotion regulation. Although both DBT-BED and ACGT reduced binge eating, DBT-BED showed significantly fewer dropouts and greater initial efficacy (e.g., at posttreatment) than ACGT. The lack of differential findings over follow-up suggests that the hypothesized specific effects of DBT-BED do not show long-term impact beyond those attributable to nonspecific common therapeutic factors.

On the use of propensity scores in principal causal effect estimationSTATISTICS IN MEDICINEJo, B., Stuart, E. A.2009; 28 (23): 2857-2875

Abstract

We examine the practicality of propensity score methods for estimating causal treatment effects conditional on intermediate posttreatment outcomes (principal effects) in the context of randomized experiments. In particular, we focus on the sensitivity of principal causal effect estimates to violation of principal ignorability, which is the primary assumption that underlies the use of propensity score methods to estimate principal effects. Under principal ignorability (PI), principal strata membership is conditionally independent of the potential outcome under control given the pre-treatment covariates; i.e. there are no differences in the potential outcomes under control across principal strata given the observed pretreatment covariates. Under this assumption, principal scores modeling principal strata membership can be estimated based solely on the observed covariates and used to predict strata membership and estimate principal effects. While this assumption underlies the use of propensity scores in this setting, sensitivity to violations of it has not been studied rigorously. In this paper, we explicitly define PI using the outcome model (although we do not actually use this outcome model in estimating principal scores) and systematically examine how deviations from the assumption affect estimates, including how the strength of association between principal stratum membership and covariates modifies the performance. We find that when PI is violated, very strong covariate predictors of stratum membership are needed to yield accurate estimates of principal effects.

Abstract

In longitudinal studies, outcome trajectories can provide important information about substantively and clinically meaningful underlying subpopulations who may also respond differently to treatments or interventions. Growth mixture analysis is an efficient way of identifying heterogeneous trajectory classes. However, given its exploratory nature, it is unclear how involvement of latent classes should be handled in the analysis when estimating causal treatment effects. In this paper, we propose a 2-step approach, where formulation of trajectory strata and identification of causal effects are separated. In Step 1, we stratify individuals in one of the assignment conditions (reference condition) into trajectory strata on the basis of growth mixture analysis. In Step 2, we estimate treatment effects for different trajectory strata, treating the stratum membership as partly known (known for individuals assigned to the reference condition and missing for the rest). The results can be interpreted as how subpopulations that differ in terms of outcome prognosis under one treatment condition would change their prognosis differently when exposed to another treatment condition. Causal effect estimation in Step 2 is consistent with that in the principal stratification approach (Frangakis and Rubin, 2002) in the sense that clarified identifying assumptions can be employed and therefore systematic sensitivity analyses are possible. Longitudinal development of attention deficit among children from the Johns Hopkins School Intervention Trial (Ialongo et al., 1999) will be presented as an example.

Abstract

In this article, we present a discussion of two general ways in which the traditional randomized trial can be modified or adapted in response to the data being collected. We use the term adaptive design to refer to a trial in which characteristics of the study itself, such as the proportion assigned to active intervention versus control, change during the trial in response to data being collected. The term adaptive sequence of trials refers to a decision-making process that fundamentally informs the conceptualization and conduct of each new trial with the results of previous trials. Our discussion below investigates the utility of these two types of adaptations for public health evaluations. Examples are provided to illustrate how adaptation can be used in practice. From these case studies, we discuss whether such evaluations can or should be analyzed as if they were formal randomized trials, and we discuss practical as well as ethical issues arising in the conduct of these new-generation trials.

Abstract

This article links the structural equation modeling (SEM) approach with the principal stratification (PS) approach, both of which have been widely used to study the role of intermediate posttreatment outcomes in randomized experiments. Despite the potential benefit of such integration, the 2 approaches have been developed in parallel with little interaction. This article proposes the cross-model translation (CMT) approach, in which parameter estimates are translated back and forth between the PS and SEM models. First, without involving any particular identifying assumptions, translation between PS and SEM parameters is carried out on the basis of their close conceptual connection. Monte Carlo simulations are used to further clarify the relation between the 2 approaches under particular identifying assumptions. The study concludes that, under the common goal of causal inference, what makes a practical difference is the choice of identifying assumptions, not the modeling framework itself. The CMT approach provides a common ground in which the PS and SEM approaches can be jointly considered, focusing on their common inferential problems.

Abstract

In cluster randomized trials (CRTs), individuals belonging to the same cluster are very likely to resemble one another, not only in terms of outcomes but also in terms of treatment compliance behavior. Although the impact of resemblance in outcomes is well acknowledged, little attention has been given to the possible impact of resemblance in compliance behavior. This study defines compliance intraclass correlation as the level of resemblance in compliance behavior among individuals within clusters. On the basis of Monte Carlo simulations, it is demonstrated how compliance intraclass correlation affects power to detect intention-to-treat (ITT) effect in the CRT setting. As a way of improving power to detect ITT effect in CRTs accompanied by noncompliance, this study employs an estimation method, where ITT effect estimates are obtained based on compliance-type-specific treatment effect estimates. A multilevel mixture analysis using an ML-EM estimation method is used for this estimation.

Abstract

Thalamic alterations have been reported in autism, but the relationships between these abnormalities and clinical symptoms, specifically sensory features, have not been elucidated. The goal of this investigation is to combine two neuroimaging methods to examine further the pathophysiology of thalamic anomalies in autism and to identify any association with sensory deficits. Structural MRI and multi-voxel, short echo-time proton magnetic resonance spectroscopy ((1)H MRS) measurements were collected from 18 male children with autism and 16 healthy children. Anatomical measurements of thalamic nuclei and absolute concentration levels of key (1)H MRS metabolites were obtained. Sensory abnormalities were assessed using a sensory profile questionnaire. Lower levels of N-acetylaspartate (NAA), phosphocreatine and creatine, and choline-containing metabolites were observed on the left side in the autism group compared with controls. No differences in thalamic volumes were observed between the two groups. Relationships, although limited, were observed between measures of sensory abnormalities and (1)H MRS metabolites. Findings from this study support the role of the thalamus in the pathophysiology of autism and more specifically in the sensory abnormalities observed in this disorder. Further investigations of this structure are warranted, since it plays an important role in information processing as part of the cortico-thalamo-cortical pathways.

Abstract

Cluster randomized trials (CRTs) have been widely used in field experiments treating a cluster of individuals as the unit of randomization. This study focused particularly on situations where CRTs are accompanied by a common complication, namely, treatment noncompliance or, more generally, intervention nonadherence. In CRTs, compliance may be related not only to individual characteristics but also to the environment of clusters individuals belong to. Therefore, analyses ignoring the connection between compliance and clustering may not provide valid results. Although randomized field experiments often suffer from both noncompliance and clustering of the data, these features have been studied as separate rather than concurrent problems. On the basis of Monte Carlo simulations, this study demonstrated how clustering and noncompliance may affect statistical inferences and how these two complications can be accounted for simultaneously. In particular, the effect of the intervention on individuals who not only were assigned to active intervention but also abided by this intervention assignment (complier average causal effect) was the focus. For estimation of intervention effects considering noncompliance and data clustering, an ML-EM estimation method was employed.

Abstract

To examine the structure of emotions and affective dysregulation in juvenile delinquents.Fifty-six juvenile delinquents from a local juvenile hall and 169 subjects from a local high school were recruited for this study. All participants completed psychometric testing for trait emotions followed by measurements of state emotions under two conditions (free association and stress condition). Finally, delinquent participants completed a detailed assessment of past trauma using the Childhood Trauma Interview (CTI).Delinquents exhibit significantly higher levels of negative state and trait emotions when compared to a high school sample. In the delinquent sample chronicity of physical trauma affects the longstanding variable of trait emotionality and severity of trauma, specifically emotional abuse and witnessing violence, shapes negative emotional outcomes in state emotionality. In addition, delinquents appear to experience a wider range of emotions than the comparison sample and were more likely to experience a confluence of state emotions of sadness and anger under stressed conditions.Adolescent delinquents appear to have a different experience of negative emotions than comparison adolescents. The experience of emotions appears to differ in state and trait conditions. These emotions may be related to childhood experiences of trauma.

Abstract

The ability to decode letters into language sounds is essential for reading success, and accurate identification of children at high risk for decoding impairment is critical for reducing the frequency and severity of reading impairment. We examined the utility of behavioral (standardized tests), and functional and structural neuroimaging measures taken with children at the beginning of a school year for predicting their decoding ability at the end of that school year. Specific patterns of brain activation during phonological processing and morphology, as revealed by voxel-based morphometry (VBM) of gray and white matter densities, predicted later decoding ability. Further, a model combining behavioral and neuroimaging measures predicted decoding outcome significantly better than either behavioral or neuroimaging models alone. Results were validated using cross-validation methods. These findings suggest that neuroimaging methods may be useful in enhancing the early identification of children at risk for poor decoding and reading skills.

Bias Mechanisms in Intention-to-Treat Analysis With Data Subject to Treatment Noncompliance and Missing Outcomes.Journal of educational and behavioral statistics : a quarterly publication sponsored by the American Educational Research Association and the American Statistical AssociationJo, B.2007; 33 (2): 158-185

Abstract

An analytical approach was employed to compare sensitivity of causal effect estimates with different assumptions on treatment noncompliance and non-response behaviors. The core of this approach is to fully clarify bias mechanisms of considered models and to connect these models based on common parameters. Focusing on intention-to-treat analysis, systematic model comparisons are performed on the basis of explicit bias mechanisms and connectivity between models. The method is applied to the Johns Hopkins school intervention trial, where assessment of the intention-to-treat effect on school children's mental health is likely to be affected by assumptions about intervention noncompliance and nonresponse at follow-up assessments. The example calls attention to the importance of focusing on each case in investigating relative sensitivity of causal effect estimates with different identifying assumptions, instead of pursuing a general conclusion that applies to every occasion.

Sex differences in brain activation elicited by humorPROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICAAzim, E., Mobbs, D., Jo, B., Menon, V., Reiss, A. L.2005; 102 (45): 16496-16501

Abstract

With recent investigation beginning to reveal the cortical and subcortical neuroanatomical correlates of humor appreciation, the present event-related functional MRI (fMRI) study was designed to elucidate sex-specific recruitment of these humor related networks. Twenty healthy subjects (10 females) underwent fMRI scanning while subjectively rating 70 verbal and nonverbal achromatic cartoons as funny or unfunny. Data were analyzed by comparing blood oxygenation-level-dependent signal activation during funny and unfunny stimuli. Males and females share an extensive humor-response strategy as indicated by recruitment of similar brain regions: both activate the temporal-occipital junction and temporal pole, structures implicated in semantic knowledge and juxtaposition, and the inferior frontal gyrus, likely to be involved in language processing. Females, however, activate the left prefrontal cortex more than males, suggesting a greater degree of executive processing and language-based decoding. Females also exhibit greater activation of mesolimbic regions, including the nucleus accumbens, implying greater reward network response and possibly less reward expectation. These results indicate sex-specific differences in neural response to humor with implications for sex-based disparities in the integration of cognition and emotion.

Abstract

Although schizophrenia is strongly hereditary, there are limited data regarding biological risk factors and pathophysiological processes. In this longitudinal study of adolescents with 22q11.2 deletion syndrome, we identified the catechol-O-methyltransferase low-activity allele (COMT(L)) as a risk factor for decline in prefrontal cortical volume and cognition, as well as for the consequent development of psychotic symptoms during adolescence. The 22q11.2 deletion syndrome is a promising model for identifying biomarkers related to the development of schizophrenia.

Learning when school is not in session: a reading summer day-camp intervention to improve the achievement of exiting First-Grade students who are economically disadvantagedJOURNAL OF RESEARCH IN READINGSchacter, J., Jo, B.2005; 28 (2): 158-169

Abstract

This paper proposes growth mixture modeling to assess intervention effects in longitudinal randomized trials. Growth mixture modeling represents unobserved heterogeneity among the subjects using a finite-mixture random effects model. The methodology allows one to examine the impact of an intervention on subgroups characterized by different types of growth trajectories. Such modeling is informative when examining effects on populations that contain individuals who have normative growth as well as non-normative growth. The analysis identifies subgroup membership and allows theory-based modeling of intervention effects in the different subgroups. An example is presented concerning a randomized intervention in Baltimore public schools aimed at reducing aggressive classroom behavior, where only students who were initially more aggressive showed benefits from the intervention.

Abstract

Randomized trials often face complications in assessing the effect of treatment because of study participants' non-compliance. If compliance type is observed in both the treatment and control conditions, the causal effect of treatment can be estimated for a targeted subpopulation of interest based on compliance type. However, in practice, compliance type is not observed completely. Given this missing compliance information, the complier average causal effect (CACE) estimation approach provides a way to estimate differential effects of treatments by imposing the exclusion restriction for non-compliers. Under the exclusion restriction, the CACE approach estimates the effect of treatment assignment for compliers, but disallows the effect of treatment assignment for non-compliers. The exclusion restriction plays a key role in separating outcome distributions based on compliance type. However, the CACE estimate can be substantially biased if the assumption is violated. This study examines the bias mechanism in the estimation of CACE when the assumption of the exclusion restriction is violated. How covariate information affects the sensitivity of the CACE estimate to violation of the exclusion restriction assumption is also examined.

Abstract

This study examined various factors that affect statistical power in randomized intervention studies with noncompliance. On the basis of Monte Carlo simulations, this study demonstrates how statistical power changes depending on compliance rate, study design, outcome distributions, and covariate information. It also examines how these factors influence power in different methods of estimating intervention effects. Intent-to-treat analysis and complier average causal effect estimation are compared as 2 alternative ways of estimating intervention effects under noncompliance. The results of this investigation provide practical implications in designing and evaluating intervention studies taking into account noncompliance.